1. Field of the Invention
The present invention relates to a photographic microfilm recording device, or a microfilm camera, for photographically recording a number of images of documents on a microfilm on a reduced scale.
2. Description of the Prior Art
Of numerous photographic microfilm recording devices or microfilm cameras, the microfilm camera has been suggested in which, while the size of a single frame in the microfilm corresponds to the size of a document to be recorded on the microfilm, both of a single-size image and a double-size image can be photographically recorded. In this system, for retrieving purpose, a blip marking is also photographically recorded on the microfilm at a location in the vicinity of and peripheral to each image recorded on the microfilm.
More specifically, with the prior art microfilm camera referred to above, the images are photographically recorded on a reduced scale on the microfilm in a fashion which will now be described with reference to FIG. 13. FIG. 13 illustrates a portion of the microfilm M, i.e., a strip of light sensitive film designed to bear a miniature photographic copy of documents. That portion of the microfilm M is shown to bear a single-size image P1 and a double-size image P2 positioned one after another in a direction lengthwise of the microfilm M.
As shown in FIG. 13, according to the prior art microfilm photographing system now under discussion, a blip marking B is photographically recorded along one side edge of the microfilm M and adjacent one corner of each of the recorded images P1 and P2 on a leading side with respect to the direction of sequence of photographing. In other words, only one blip marking B is photographically recorded at a leading position along one side edge of the microfilm M for each recorded image P1 and P2 regardless of the size of an image area in which the associated image P1 and P2 is recorded. So far shown, the recorded image P1 represents a single-size image of one page, for example, either a B5-size format or an A4-size format, of a book whereas the recorded image P2 represents a double-size image of two pages (and, hence, B4-size format or A3-size format) of the book.
Apart from the above, the Japanese Laid-open Patent Publication No. 60-95525, published in 1985, discloses a microfilm camera system having a capability of photographically recording a number of types of blip markings B. However, even with this prior art microfilm camera system, blip markings B of only selected one of the types can be photographically recorded, one for each image area on the microfilm, along one side edge of the microfilm in a manner similar to that shown in and discussed with reference to FIG. 13.
As is well known to those skilled in the art, images recorded on the microfilm are so miniature that, in most cases, unless the use is made of a microfilm reader or printer or a combined reader and printer, what is expressed in the microfilmed image cannot be legible. Therefore, when one or some of the microfilmed images are desired to be viewed through the microfilm reader or to be copied through the printer, a controller-based retrieval is generally carried out to locate such one or some of the microfilmed images. More specifically, an operator of, for example, the microfilm reader has to input, into a retrieval system, an address of one of the microfilmed images which is desired to be viewed through a screen of the microfilm reader, so that the retrieval system can browse the microfilm to locate such one of the microfilmed images and then to cause it to be displayed through the reader screen. The retrieval system while browsing the microfilm counts the number of the blip markings, one for each microfilmed image, and issues a stop command to interrupt a transport of the microfilm when the count of the blip markings coincide with a particular value assigned by the input address, thereby enabling the particular microfilmed image to be displayed through the reader screen.
Referring again to FIG. 13, where only one blip marking B is allocated to each microfilmed image P1 or P2 regardless of the size of the image area thereof on the microfilm M, a problem has been encountered in that a desired portion of the double-size image P2, i.e., the image microfilmed in a size double the single-size image P1, cannot be easily retrieved and complicated and time-consuming procedures are required to make that desired portion of the double-size image P2 displayed through the reader screen. In the case of the prior art microfilm camera specifically designed for use with documents such as books, a two-page spread of a book representing the double-size image of B4-size or A4-size format is photographed on a reduced scale as shown by the double-size image P2, with one blip marking B photographically recorded for that double-size image P2. Therefore, the retrieval on page basis requires a preparatory calculation to determine how many pages are to be transported to a desired page of the microfilmed transcript of the book to locate the desired page, followed by a manual procedure to bring the image of the desired page in register with the reader screen.
By way of example, let it be assumed that the microfilm bears a series of the single-size image P1 corresponding to page 1 of a book and the double-size images P2 corresponding to the subsequently succeeding pages of the book and that the user wishes to view a microfilmed image of page 9 of the book. According to the prior art system, when such microfilm is placed on the microfilm reader having the controller-based retrieval system, the user has to calculate either from memory or by heart how many blip markings have been recorded from the first blip marking corresponding to the microfilmed image of page 1 to that of page 9 and then to input an address value of 5 corresponding to the number of the blip markings calculated from the microfilmed image of page 1 to that of page 9. The inputting of the address value of 5 will result in a display, on the reader screen, of the microfilmed image of page 8 partly because page 8 and page 9 of the book form a two-page spread recorded on a single image area and partly because the corresponding blip marking has been recorded at a position along one side edge of the microfilm and adjacent a corner of that image area on the leading side with respect to the direction of sequence of photographing. Once the microfilmed image of page 8 has thus been displayed on the reader screen, the user then has to make an manual adjustment to bring the microfilmed image of page 9 in position ready to be displayed through the reader screen. This is indeed complicated and time-consuming.